Indigobush Twig Borer
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Contents |
Hosts
Indigobush. Indigobush is the only known host.
Range
Collected from Washington and Sharkey Counties in Mississippi and Chico County in southeastern Arkansas.
Description
Adult
Grayish brown moth that is somewhat bell shaped when wings at rest (Heinrich 1929). Leading apical half of forewing with three alternating orangish brown and metallic streaks; triangular orangish brown patch occurs in apical third of forewing, crossed by three metallic bars with distinct black dashed between bars. Leading basal half lighter than rest of wing. Hindwings uniformly grayish brown. Wingspans of 13 to 17 mm. Head and thorax semilustrous and uniformly colored orangish yellow to brown.
Larva
Plump, pale white with brown head and light brown pinacula; about 14 mm long when mature.
Pupa
Light brown and about 12 mm long.
Biology
Adult moths have emerged from plants kept in cages during May and June in Mississippi. Larvae develop in infested shoots and make only short tunnels in twigs and terminals. Pupation occurs in burrows, and the pupae move partly out of the shoots for moth emergence. Enlarged shoots have been found after May and June emergence, indicating delayed emergence or possibly more than one generation per year.
Injury and Damage
Infested shoots appear stunted and curl apically. Apical portions of shoots often wither and die back. Clumps of fine brown frass may be present either at the shoot apex or at the juncture of a leaf petiole. Cutting open the swollen shoot reveals the burrow and sometimes the larva. Infested parts of terminals and twigs appear swollen and become greatly enlarged, sometimes reaching two or three times their normal diameter. Some shoots seem to be appropriated almost entirely for the development of larvae. Pupal skins often protrude from enlarged shoots. Heavy infestations can cause noticeable dieback of individual plants, but infestations are usually localized and rarely cause serious damage.
Gallery
Control
Natural controls have not been observed, and direct controls have not been needed.
References
Solomon, J.D. 1995. Guide to insect borers of North American broadleaf trees and shrubs. Argic. Handbk. 706. Washington, DC: U.S. Department of Agriculture, Forest Service. 735 p.
